If you have a parasite, as you stated.
He has internal parasites.
(the Jungle Parasite Clear medication) and his stomach is still getting bigger.
I am not there, I only know what you state,
If it was the Camalanus parasite everything would be indeed infected!
Did you know it can take 6 months before it even begins to show itself?
Not all fish will show it in their poo either until they are more heavily infected.
Obviously if all is well then maybe you didn't have a parasite as you thought.
Do a search on the camalanus worm, It's oft times refered to by people as the Devil's worm.
I'm glad things appear better for you,
Hopefully all will continue well for you..